GEARBOX WITH REDUCED ENCUMBRANCE

摘要

A gearbox with reduced encumbrance, comprising a primary shaft (12) carrying primary gearings (30, 31, 32, 33, 34, 35), a secondary shaft (36) parallel to a primary shaft (12) which carries secondary gearings (37, 38, 39) of odd-number gears and secondary gearings (40, 41, 42) of even-number gears which can be activated in engagement with the primary gearings of the primary shaft (12) by means of a cam shaft (43) coaxial with the secondary shaft (36), carrying cams (54, 55, 56, 57, 58, 59), spaced axially and angularly and helicoidally offset with respect to each other, by an angle a, so as to be brought one at a time in correspondence with the secondary gearings of the secondary shaft which follows the rotation of the cam shaft, rotation means (29, 50) of the cam shaft being envisaged with respect to said secondary shaft, and also means for the selective engagement (51, 52, 53, 49) between primary gearings and secondary gearings with the controlled rotation of the cam shaft with respect to the secondary shaft, the engagement means consisting of ferrules (52) slidingly positioned in openings (51), angularly and helicoidally offset with respect to each other in hollow side walls of the secondary shaft in a complementary position with respect to that of the cams, each secondary gear comprising at least one seat (49) for receiving a ferrule (52) when raised, in which a second primary shaft (11) is envisaged, coaxial to the first primary shaft (12) and carrying the primary gearings of odd-number gears, whereas the first primary shaft (12) carries primary gearings of even-number gears, each of the two primary shafts integrally carrying a clutch (13, 14) which is coaxial and can be independently actuated, wherein the cams are in a number of at least two for each secondary gearing, which, in turn, envisages at least two seats (49) for the ferrules (52).